Induction-motor.



B. MOCOLLUM.

mnncmu MOTOR.

[LPLIGATION FILED MAR. 3. 1911 1 038 775 Patented Sept. 17,1912.

2 SHEETS-SHEET 1.

F 7 r E5 I I wpwtoz Jill/'10 /W 0///1/Il attoww B. MGCOLLUM. INDUCTION MOTOR.

APPLICATION FILED MAR.3.1911.

1,038,775. Patented Sept. 17,1912.

2 SHEETS-SHEET 2.

l I E E Fe l" /06 /fl0 Z00 J00 J05 J00 600 700 600 gm M00 to be heated. shall contain a v of such short length that the total resistance will not be great enough to reduce seriously the efficiency of the motor.

I have given my invention several practical embodiments, some of which I show in the accompanying drawings. In these illustrative embodiments I make use of the re sistance element of the material specified, portions of which are of very small cross section, somewhat ribbon like or filament like in shape, and the adjoin" ortions which may boot the same cr d? different material are relatively massive nnd adapted for connection to the conductors of the circuit in which the element is to be used. By making these intermediate rtions of relatively arge size, and the cements of reduced cross section sullicienfly short the total running resistance of the rotor circuit may be kept low, while the portions of the relatively small cross section are particularly adapted to be rapidly heated, having small capacity for absorbing heat, and for the same reason as rapidly cooled.

Of the drawings;-Figure l is an and elevation of the motor, the rotating element of which is equipped with the device of my invention. Fig. 2 is a side elevation of the 4 rotor of this motor. Fig. 3. is a. view in elevation on a somewhat larger scale than Fig. 2, to show the relation of the parts of the starting device. Fig. 4 is a sectional view on the line 10-10 of Fig. 1, showing one construction of resistance element which I have found desirable. F i 5 is a view in' perspective ofa portion oi a rotor showing a simplified form of my invention. Fig. 6 is a view similar to Fig. 4, of a slightly different mechanical arrangement. Fig. 7 is a view of a portion of a resistance element of slightly different form. Fig. 8 is a showing of some curves which -I have obtained from actual tests upon metals which I use according to my invention, and of other metals which I found not suitable for use. Fig. 9 isa diagram explaining the effect of the resistance elements under running conditions.

Referring particularly to F ig. 1, l0 designates the stator and 11, the rotor. The

.rotor winding, as shown, is of the squirrel cagc type, the resistance elements of my invention being inserted in one or more of the short circuiting end rings. In the case illustrated in Figs. 1 and 2 there are two of these rings 12 and 12'. on each end of the rotor although it will be seen that one or a greater number than two may be used if. A description of one of them' will sufioe, since all of them are The ring is made up 0! a central edgewise band of the material having the characteristiea above described, such as. ironor nickel, and spaced embracing members 13, 13 of larger cross section than the ribbon like band 12 and relatively msmivo-i'n' form...

The members 13, 13'are identically alike in form, and are 5 accd in pairs one on each side of the band and riveted or otherwise attached thereto. From their outer sides project cars 15, 15 throu h whichvconnection is made to the con uctors 16 of the rotor by.any suitable method.

The portions -1 7 of the band ifljbetween the members 13, 13 are of suchdimension as to section and length as to be heated by the starting currents of themotor to and above the critical temperature value. Upon starting therefore, a very resistance is interposed in the ath-of the current and the motor starts withhigh torque." ilpon rotation, however, thecurrontiis out down by the counter elcctro motive force-due to rotation and the temperature, and. therefore the resistance falls rs idlyte its value, the normal in load current being below the critical value. By virtue of the enlarged portions 13, 13' which 7 may :be made of a more conductive .material than" iron or nickel if desired, the running resistance of the device is kept as low as desired.

The double squirrel cage form shown in Figs. .1 and2 is particularly advantageous, since with this type of constri rctioh fewer resistances are in series-in any, giyiurcircuit than when but a single squirrelcage is used. It is to .be observed that there are two rcsistanceriiigs on each end of the rotor and that every second conductor 16 is connected to the same ring. Generally stated, in this embodiment of my invention I make use of n rings on each end of the rotor, and connect every nth conductor'to the samering. It is' to be understood, however, that it is not necessary to use several rings of the type described on both ends of the rotor, but all t c rotor bars at one end of the rotor may connected to a. short circuiting element ring of the usual or any. desired type.

In the embodiment of my invention shown in Fig. 5, a slight mechanical variation in structure is disclosed, in which alternated attenuated and massive resistance sections are formed by a band 18 which abuts the ends of the conductor bar 19, being held thereto by the spaced massive sections 20, suitable fastening devices, such as screws 22, serving to hold the parts in position.

In Fig. 6 the same result secured by coupling the attenuated band 21 with the massive lugs 22, spaced from one another, the conductor bars 23 being secured by suitmaww Nicicei is very much mare rasis-taniz msxiw iion; and is therefiire a satisfacim y mgilfi'iflto use a comm As make; in (-SXXEIIIOB with 5mm possesses the characteriaiics I have found dusirable, no impairmeni f the openuiing efi'icienay results .fmm dais eigaiizfii i, and the deterioraiimi of the meiai. chi-s m nxidaiinn is eiimirzated. 52m: 8.10m may used if the temperature satcmriaxi m 2H pbint of oxidaiiun. V

I have shown diagrammatic-:21 y in Fi a strip er band 9f imzi wastes? aim as a'iam g described, ii being undsrsiesd that Him structure may be embodied in any 0? die forms of msistarice fii ameaia herein befere described. 2

Referring to Fig. 3 ii, wiiibe sax; flmt- I have shown a. number of (Inn'sare resistance current cnrves. The CEZYE'QS' numbered 1 am? 2 am raaisisnc e currmt curves' of iron and niek zlrrrespectivaiyz It wiii be seen that via certain witicai surrrzm value these curvs rise abrizptiy, incrsnsing ta :1 manifold value. (in the ether 5121x151 refarting to curves 3, 4 and 5, which aye re spectively the curves far copper, Hmgnasiism and aluminum, it W213 be seen that them is no such abrupt rise 'lh'e peinis afi Wiiiciz these curves terzz inati represent snftiening r melting points of the meta] EllffQilfi WiiiCiE 1i isimposx sibie to make 0f them i0? ni'ivimas z'easnn that ilhfiil g ldfififiy is 1* stroyed hing bafsie til-ta i fli fi'i gwizz-i cf critical current vain? Ema bea'zi rilfih iii is to he noted 2112i;-

siiz'vac: 1 and 2 is? iron am: nick-e! dcnot ha melfiirig gioint until 10:2 Eitfii' abmgii, ri s in ra sistance has ta 'en piaca As siateti 'at the aiziat, tin e aiemams, wF' ch are adagite 0 imam g at siaring and a relaiveiy iew v under rm nagcoziditions, are in be ief pk .nmnentiy in ,ciirciiit. This is imporirmt, Rhine for mechai iicai simpiisity, imi, mi'sz'aa especiily because of fize impmved gamer factor which the impari. in the main? reason for this impnwed power faster may be readiiy seen by z'eferenoe 1'10 the ia mm in F 1g. 9. Hem the paraiiei i'iBfiFS'Y SF-ZfiSQEi he i'iizet-r'iion Of i318 nmgmiie instant, and the earve i Hf H? E2 under m m n mailer namai imad -R1l6fi$ fi'i'e meters $5 of ihe rotor are mtatmg m the ame dzmciwn the 33% size fiaid Emit at siigiiiy iewer geared. T mnducwrs w WEE,- iiismefnm, haw,- ixafizice ii them an eiQ-eia'mmti'a e fax-w which is iif thai ii gas-m5 03f iigi, am: which is ap 1mximatgy a sine wave, in pha auwiii-fihe magnet-ism. 2 f arm the resmnw i 533 5mm, is, usaaiiy he 0%.. aiza-curreniviil be a sina wave and tile rz'saitant wiiswiiwz 0% m miss aments mil f'fiQiE-i" 142 in a mcs guadi atiimiwiith he avmg Ema 21m inertia are kept gammnenfiy in flak circuit the rs'istznce will n ate ma ler the passage of tiw. aiiematin' mzrmni this puiisa tim king atigmemed by the 312w fireigsiezzey e? the siiemaiing czzrreiit.

ili'zniiai m: as 11mg as "Hawaii; 5% afimz iis ii'ki'sifi wine gzmximaiiy #speaizing. it. feiifiws i nite that {'ifil'ifili in thuse: 32am fihai are appmatehing mideiie paint us? axis if it: iieid wiii earn ie-rger curmtiis 22m ihaagham which. Rave posi iien. The rsuitaiiti'ziagnetnmsti W3 is? v 0%? die cuzx'ezits will i-hemfiare have a min mum: in phase with the limit; mag miisizz ami the efi'fest is similar t0 that of s kaciiiig current iii the rotsr. Tim rot/Gr 3 Ciiiffi'fi'iiii wan therefore Eva mafia w supply a part car ail 0f the magnetism of the mat-3r, time. relieving the primary winding'oi the wrwsgmnding 0f the exciting current :mc} heme raiisiag the pawer the snowy. Farting, this transferense 9i he afifiiiifig'lilifl from the stator 0 the wiaiiwEy 10w rmissmfica mica" iH-CNEELQS ihe ei'iisisncy cf the mater.

liiff, simwsi, ms the cmzves 1 iliais tima miawazitzigamzei iiesirabie iimi a ifiliitifi wt agniisrd suddeiily but gratin-3213*.

Wiiii beat furr Q. ()1 imzexiiiaai 219w imam" ti) 'siie, l desk. to havs'ii fii'l-ISifififi 111% many madifisatisns may m made by 118% i Ed in the art withmit ci epairting in any herein. Mixer 1 ilesire Win' in the ciai ail we m'icaiiom that aim? 'szhiihiri we gaixeric 0f inveniiaa.

i m cir E1, him-awn we resizimnce eimma w pafiiwl i zxis mean faster (if 3&5

apprecifihiv i'me is iaizezi fay m- 33% 1 have Shaw and iifirlrf b fiii @353 1212 generic $3i5fit..9f my 551%?!" Having thus described the inventisn Wiliii w r the m nim"?! 1% at a critical current value and so proporcage (finding comprising a resistance eleuicnt characterized by an abrupt rise of resistance at. a critica current value. V

2. In an induction motor of the squirrel cage typc,-conduct0r bars, and a short cir-V ailing device permanently connected in i-ircuit with the conductor bars ofthe squirltl cage winding, said device comprising a '-i- -i. tancc element having portions of re- (llltltl cross section of a material having a pnsiliflf temperature cocllicient of resistance and a resistance curve characterized by an abrupt rise of resistance at a critical current value. and so proportioned that the darling; currents of the motor are above the critical current value and the normal load currents of the motor are below the critical current value.

3. in an induction motor of the squirrel cage type, conductor bars, and a short circuil'ing device permanently coiiiiccted in cir- :llil with the conductor bars of. the squirrel rage winding, said device comprising a resislancc conductor of a material having a resistance curve characterized by anabruptrise of resistance at a critical value of'rising current and so proportioned as that the starting currents of the motor are above the critical current value and the normal load currents of the motor are below the critical current value.

t. In an induction motor of the squirrel cage l ypc, a short circuiting device permanently connected in circuit with the conductor. barsot the, squirrel cage winding, said device comprising a resistance conductor havingportions which are alternately attcnualed and massive in cross sectionand of a material having a resistance curve characterized by an abrupt rise of resistance at a critical current value and so proportioned that the starting currents of the motor are above the critical, current value and the normal load currents of the motor are below the critical current; value.

In an induction motor of the squirrelv cage type, conductor-bars, and a short circuilimg device permanently connected in circuit with the conductor l) rs of the squirrel cage windiug,said device comprising a resistance conductor having portions which 1 are alternately attenuated and massive in 'cross section, said attenuated portions being of a mater al having a resistance curve clnn'ac'terized by an abrupt rise of resistance "*tioned as that the starting currents of the motor, are above the critical current value and the normal load currents of the motor are below the critical current value.

(i. In an induction motor of the squirrel cage type, conductor bars, and a plurality of short circuiting devices permanently connected in circuit with the conizlinztor bars of the squirrel cage winding, each of. which has portions of relatively low resistance eonance, said portions of high resistance being characterized by an abrupt rise of'resistance at a critical value of currenband so proportioned that the said critical value of current will lie between the starting current and the normal load current of the motor.

7. An induction motor, of the squirrel cage type having conductor bars, two or more short circuiting end rings on its mo tor, portions of which rings are alternately attenuated and massive in cross section, and permanent connections between one series of conductors of said rotor and one of said rings, and like permanent connections between the other series of said conductors and the other rings.

8. An induction motor, of the squirrel cagetype having conductor bars} two or more short circuiting end rings on said attenuated and massive incross section; permanent connections between one series'cf conductors of said rotor and one of said rings; and like permanent connections between the other series of said conductors and the other rings; said ring portions of re-' duced cross section being of-ii material hav-' ing a relatively high positive temperature eoefiicicnt of resistance, and a temperature current,curvecharaeterized by an abrupt rise of resistance at-a certain critical cur rent' value whiclrlies between the starting motor.

-9.-An induction .motor, of the squirrel cage type having conductor bars; two or; more short 1 circuit-ing.cnd rings onv rotor, said rings havmg'alternated attenuated and massive portions of which the attenuated portions are of a material having a high positive temperature coellieient; of resistance, and a temperature current curve characterized by an abrupt rise of resistance at a certain critical current value which lies between the starting current. and'the normal load current'of the motor; a series of rotor conductors spaced approximately one pole, pitch or less being permanently connectml' rotor conductors similarly spaced and simi-' larly connected .to others of the said rings.

10. A short circuiting end ring forinduction motors comprising an edgewisc thin band of matcrial'hav'ing a temperature rcsist-a'nce curve character-ind by an abrupt rise of resistance at a defined critical value of current, and spaced connecting portions of relatively greater cross-section adapter to beconncctcd to the conductors of the rotor winding.

11. A short-circuiting end ring for induc -tion motors-comprising an ixlgewise thin band of material having a temperature rcrotor having portions which are alternately nected by portions of relatively high reaistcurrent and the normal load current of the mo [1'5 to one (if said rings; andqothervseries of sistance curve having an abrupt rise of resistance at a defined critical value of temperature, and spaced connecting portions of relatively greater cross section adapted to be connected to the conductors of the rotor winding.

12. A short-circuiting end ring for induction motors comprising a band of material having a temperature resistance curve characterized by an abrupt rise of resistance at a defined critical value of current said band having alternated attenuated and massive portions.

13. In an induction motor, a resistor comprising a material having a resistance current curve characterized by an abrupt rise of resistance at a critical current value, and a coating on said conductor of a material substantially non-oxidizable at the temperature reached by the body of said resistor under the normal starting currents of the motor.

H. In an induction motor, a resistor comprising a material having a resistance curance elements permanently connected in circuit therewith, and comprising conductors of a magnetic material characterized by an abrupt rise of resistance at a critical current value and so proportioned that the normal starting currents are above this critical current value and the normal full load currents below said critical current value.

16. In an induction motor, the combination with a secondary Winding; of resistance elements permanently connected in cir- (uit therewith, said resistance elements comprising conductors of iron, said conductors being so proportioned that the normal starting currents are above the critical current value and the normal full load currents below the critical current value.

17. In an induction motor, the combination with a secondary winding; of resistance elements permanently connected in circuit therewith, said resistance elements comprising conductors of iron coated with nickel, said conductors being so proportioned that the normal starting currents are above the critical current value and the normal full load currents below said critical current value.

In testimony whereof I have hereunto set my hand in presence of two subscribing \vitnesses.

BURTON lilctOLLUhI.

Vitnesses.

Airriir'n IA. Buns"; G. M. Srtiounn. 

